在供电系统中用来校验电气设备动稳定性的是三相短路电流的( )。

A．最大值

B．最小值

C．冲击值

D．有效值

—Have you made up your mind () the chance to go to France
—No. I’m practicing () the French language

A. to give up; to learn

B. to give up; learning

C. giving up; to learn

D. giving up; learning